Differences in life-history and aging in two clonal groups of Daphnia cucullata Sars (Crustacea: Cladocera)

Life-history traits were compared in twenty-two clones of Daphnia cucullata from the pre-alpine lake Klostersee in southern Germany. Clones were kept under standardized conditions (18 °C; 16:8 L/D) both singly and with 25 females per glass. Clones belonged to two genotype groups distinguished by enzyme electrophoresis. 11 of the clones had the genotype FM at the phosphate glucose isomerase locus and 11 the genotype MM. Neonates and adults of the age class 10 to 21 days were larger in one group (FM) than in the other group (MM). The size specific growth rates within any age class depended on age and body size and differed between the genotype groups. The fecundity of young FM animals (< 16 days) was significantly higher than that of MM animals, but for older females fecundity did not differ significantly. Senescence started about 6 days earlier in FM than in MM. The data are consistent with results of a field study on Daphnia cucullata in the Klostersee (Jacobs, 1990).